Hydrovac machines are (often) truck-mounted systems that spray water onto dirt at high pressure and utilize a high-strength vacuum system to lift the resulting water and dirt (i.e., mud) mixture. These systems are used for excavation, cleaning (of storm sewers and the like), and other purposes. A single tank disposed on the back of a truck includes a water-storage section and a debris-storage section. The system includes a blower that draws the mud into the debris section, where it is separated from the suction air. The suction air, now substantially free of debris, is filtered and drawn through the blower (which, again, creates the suction). Discharge air from the blower is passed through a muffler to reduce the sound at the muffler discharge outlet. Additionally, a bypass system is utilized to prevent the blower from dead-heading as it draws mud and debris during operation. The bypass system draws air from ambient, via a bypass muffler system, and into the blower inlet. This allows the blower to operate efficiently and reduces the risk of blower damage, as volumes of heavy mud and other debris are sucked up. In existing systems, the discharge and bypass mufflers are discrete insulated pipes into which high-velocity air is discharged or drawn through, respectively. They are typically disposed proximate the tank, above or below the blower.